The present invention relates to an amphibious vehicle having retractable road wheels.
Except for such a vehicle designed only to use prepared firm ramps to leave the water, it is a practical necessity to provide front and rear wheel drives. Such a vehicle is shown in U.S. Pat. No. 5,531,179 Roycroft. U.S. Pat. No. 5,410,980 and U.S. Pat. No. Des. 356,056 both to Wardavoir show the Hobbycar vehicle which also has four wheel drive. A problem with four wheel drive transmission arrangements in amphibious vehicles is that space is usually restricted. For instance Wardavoir has chosen to locate the vehicle""s engine (see U.S. Pat. No. 5,410,98) in the centre of the vehicle causing the seating to be spaced in small pockets around the engine over the front and rear axles. The resulting marine performance was poor because the vehicle tended to dig its nose into the water when under way and flood the passengers. Furthermore, Wardavoir""s vehicle was uncomfortable due to seating being above the front and rear axles.
The Roycroft vehicle shown in U.S. Pat. No. 5,531,179 above had improved marine performance because the centre of gravity was moved rearwards by mounting the engine to the rear of the rear axle thus enabling a nose up attitude in the water. However the land performance was adversely affected and this was particularly so when leaving water onto soft ground, e.g. beaches. Part of the problem with the Roycroft conformation was the provision of the rear wheel differential within the transmission casing so that the transmission casing became elongated again tending to locate the engine too far to the rear.
In order to overcome the problem of poor weight distribution, so as to obtain good marine and land performance with improved ability to leave water onto soft ground, whilst retaining adequate traction, it is proposed according to the invention to provide an amphibious vehicle with an engine driving at least one rear and one front wheelxe2x80x94three, four, six or more road wheels may be used in totalxe2x80x94the engine being mounted so that its crankshaft is parallel to the front and rear axis of the vehicle and wherein the drive from the engine to the wheels is through a differential offset from the crankshaft axis to one side of the transmission. The engine can be forward or rear facing, with a power take off for a marine propulsion unit from the engine or transmission. Where the engine is rear facing, that is where the timing end is at the rear, the power take off for the marine propulsion unit is in this latter case preferably from the timing end. The road wheels should be retractable so that they are faired for improved marine performance.